Sen. Jeff Flake, Arizona's final holdout on the Senate tax bill, struck a deal to rein in a pricey tax break and received assurances that he will help negotiate permanent protections for the children of immigrants known as "dreamers."

The Senate passed a measure early Saturday, Washington time, that will lock in permanent tax breaks for corporations and the wealthy and offer a mixed bag of temporary cuts to others while adding at least $1 trillion to the national debt.

The Senate's tax-cut bill differs significantly from the version that passed the House on a party-line vote before Thanksgiving. That means both chambers must reconcile the differences in negotiations or the House must also pass the Senate version.

In discussing his support, Flake pointed to an agreement in the Senate plan to phase out a business tax break that was set to expire abruptly as making the bill more affordable.

He also sought and received a commitment from Vice President Mike Pence that he could be involved in negotiations over protections for dreamers, something that could offer a breakthrough on an immigration-related issue that has bedeviled Republicans for years.

I will support #TaxReform bill after securing language to eliminate an $85 billion budget gimmick as well as commitment from the administration & #Senate leadership to advance growth-oriented legislative solution to enact fair & permanent protections for #DACA recipients pic.twitter.com/MGbWX7JrPq

Flake said in an interview with The Arizona Republic that immigration reforms, like the tax cuts, are key to securing future economic growth.

“That has to start with (Deferred Action for Childhood Arrivals). That should be the easy lift,” he said, referring to the Obama administration-era order that provided temporary protection from deportation and work permits to dreamers. The Trump administration has announced it will end the program in March, leaving time for Congress to provide a fix.

“I’ve argued for a long time we’ve got to do that and we’ve got to do it this year," Flake said. We shouldn’t force those kids and those who are protected right now to wait through the end of the year, let alone until March.”

After multiple talks with Pence, Flake says “the administration has agreed to work with me on this, and that’s not a firm agreement and that’s not what brought me onto this bill, but it’s a nice side thing.”

Flake said he expects discussions about protections for dreamers to begin soon but doesn’t think it will be done by the end of the year, as Democrats want.

“I think it will take more than that, but this will, I think, give them some confidence that we have some people at the table who are serious about doing it. People are serious about making a law rather than making a statement. That hasn’t been the case lately.”

Flake said his support for the tax bill came after changes made the tax cuts more affordable.

“What has troubled me most about the bill is the gimmicks we use to get around exploding the debt and deficit,” Flake said.

He said the bill would give generous tax breaks for business purchases for five years and then end them outright.

“We know that if we ended something like that … we would just end up extending it,” he said, adding that it would cost an additional $500 billion. Instead, he will have an amendment to phase out the expensing break over three years after the five years it is offered.

What's in the bill

Flake had been one of the last holdouts on the bill, along with Sen. Bob Corker, R-Tenn., who had concerns about adding to the $20 trillion national debt and was the only Senate Republican vote against the plan. Corker had sought to add triggers that would have instituted tax increases if economic growth didn't match expectations, but the Senate's parliamentarian ruled out such maneuvers late Thursday.

The GOP tax plan began looking inevitable after McCain,said early Thursday he would vote for the bill.

"Though not perfect, this bill will deliver much-needed reform to our tax code, grow the economy & provide long overdue tax relief for American families," McCain said in a tweet Thursday.

"I take seriously the concerns some of my Senate colleagues have raised about the impact of this bill on the deficit. However, it's clear this bill's net effect on our economy would be positive."

The tax-cut bill would lower the federal corporate income-tax rate and grant at least temporary tax cuts to other taxpayers by adding an estimated $1.4 trillion to the national debt, according to the nonpartisan Congressional Budget Office. The nonpartisan Joint Committee on Taxation estimated it would add $1 trillion to the debt even if the plan boosts economic growth as Republicans predict.

The corporate tax cuts are expected to be made permanent, though the level of the reduction seemed in flux.

The bill reaches across many tax and spending lines, including the elimination of the Affordable Care Act's health-insurance mandate, a provision that could lead millions to drop coverage and raise rates for those who remain insured.

Public opinion leaned decidedly against the GOP plans, with about a third of those polled supporting them and nearly half opposing them, according to polling averages calculated by FiveThirtyEight.

THE GOP BEFORE TRUMP. Flake publicly criticized Donald Trump when other moderate Republicans were grumbling quietly about him. In ways, Jeff Flake became an early face of the resistance. Photo by Rob Schumacher/The Republic

IMMIGRATION AND TRADE. Flake became an influential voice on comprehensive immigration reform and preserving free trade. He also was an early advocate of opening trade relations with Cuba. Photo by Chip Somodevilla/Getty Images

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An immigration breakthrough?

Flake said he a “firm commitment” from Senate leadership and the Trump administration to pass legislation permanently protecting dreamers from deportation.

That could represent a huge breakthrough if Flake received a commitment from the White House to pass immigration legislation before the end of this year, said Frank Sharry, executive director of America’s Voice, an immigration-advocacy organization in Washington, D.C., that favors legislation to legalize undocumented immigrants.

But if Flake only received a commitment to address a permanent solution for dreamers sometime in the future, it’s unlikely Congress will pass legislation before March. That is when 689,800 immigrants brought illegally to the U.S. as children will begin losing temporary protections given to them under the Obama administration through the Deferred Action for Childhood Arrivals program, known as DACA. Of those, 25,500 DACA recipients live in Arizona, according to U.S. Citizenship and Immigration Services, the federal agency that oversees the program.

“When it comes to relief for dreamers, it’s now or never.”

Frank Sharry, executive director of America’s Voice

The vast majority of all DACA recipients, nearly 80 percent, are from Mexico, according to USCIS.

Without the temporary protections, the Trump administration could begin deporting undocumented immigrants who have lived in the U.S. since childhood, and who under the DACA program were allowed to work legally.

Immigrant advocates view December as the last best chance to get Congress and the White House to agree on legislation that would offer a pathway to legalization for DACA recipients, Sharry said.

If DACA legislation isn’t passed as part of a government spending bill, Republican leaders in Congress will have little impetus to bring up the issue next year because there will be no must-pass bill to attach it to, Sharry said.

Republican leaders may also want to avoid a divisive debate over DACA legislation within their own party, which includes conservatives vehemently opposed to passing legislation they consider amnesty.

“When it comes to relief for dreamers, it’s now or never. It either gets passed as part of an end-of-the year spending package or it’s hard to imagine it being enacted otherwise,” Sharry said.

In August 2009, Rep. Jeff Flake spent a week of his August break from Capitol Hill living a primitive, Gilligan's Island-style existence by himself on Jabonwod, Marshall Islands, a remote island in the middle of the Pacific Ocean. Here he is with a big-eyed bream. Special for The Republic

Sens. John McCain and Jeff Flake address members of the media at McCain's Phoenix office on May 28, 2014, following the release of a report stating by the Veterans Affairs that at least 1,700 veterans at the medical center were not registered on the proper waiting list, putting them at risk in the convoluted scheduling process. Charlie Leight/The Republic

Sen. Jeff Flake, in a 2015 photo, helped block an Obama-era rule protecting the privacy of Internet consumers. Flake, R-Ariz., has characterized the rule as a power grab by the Federal Communications Commission. Tom Tingle/The Republic

U.S. Sens. John McCain (right) and Jeff Flake talk with the press after their roundtable discussion with President Obama at the Carl T. Hayden VA Medical Center in Phoenix on March 13, 2015. Mark Henle/The Republic